Background: Cobalt oxide nanocubes have garnered significant attention as potential supercapacitor electrodes due to their unique structural and electrochemical properties. The spent lithium-ion batteries (LiBs) are considered as zero-cost source for cobalt oxide production.

Objectives: The aim of this work is to recover cobalt oxide from spent LiBs and study its electrochemical performance as a supercapacitor electrode material.

Methods: This study uses an electrodeposition method to obtain cobalt oxide honeycomb-like anodes coated on Ni foam substrates from spent Li-ion batteries for supercapacitors applications. The effect of annealing temperature on the cobalt oxide anode has been carefully investigated; 450ºC annealing temperature results in nanocubes on the surface of the cobalt oxide electrode. X-ray diffraction confirmed the formation of the Co_-3O_-4-NiO electrode.

Results: The Co₃O₄-NiO nanocubes electrode has shown a high specific capacitance of 1400 F g^-1 at 1 A g^-1 and high capacitance retention of ~96 % after 2250 cycles at a constant current density of 10 A g^-1 compared to 900 F g^-1 at 1 A g^-1 as for prepared Co3O4 honeycomb.

Conclusion: This strategy proves that the paramount importance of Co₃O₄-NiO nanocubes, meticulously synthesized at elevated temperatures, as a supremely effective active material upon deposition onto transition metal foam current collectors, establishing their indispensability for supercapacitor applications.